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The Nonpoint Sources and Transport of Baseflow Nitrogen Loading Across a Developed Rural-Urban Gradient

Publication ,  Journal Article
Delesantro, JM; Duncan, JM; Riveros-Iregui, D; Blaszczak, JR; Bernhardt, ES; Urban, DL; Band, LE
Published in: Water Resources Research
July 1, 2022

Nonpoint source urban nutrient loading into streams and receiving water bodies is widely recognized as a major environmental management challenge. A dominant research and management paradigm assumes that loading primarily derives from elevated stormwater. However, baseflow can account for a large portion of total loading, especially for low development intensity watersheds which comprise the largest urban areas. We investigated the sources and drivers of nonpoint source baseflow nitrogen loading across 27 headwater catchments in the urbanized Piedmont region of North Carolina, USA. Nitrate isotopes, predictors of concentration-discharge (CQ) slopes, and predictors of mean annual total dissolved nitrogen (TDN) loading suggest that wastewater was a major baseflow nonpoint source of nitrogen across developed catchments likely contributing 61% of nitrate loading from septic served catchments and 49% from sewer served catchments. Our findings suggest that subsurface TDN was abundant, loading was largely transport limited, and the hydrogeomorphic position of sanitary infrastructure strongly influences transport. We developed an empirical model showing catchment loading increased with the topographic wetness index of sanitary sewer location, convergent sloping land area, parcel density, and residual agricultural landcover (R2 = 0.78). We extended this model to the study region's 1,436 developed small (0.3–20.8 sq km) catchments. We estimated up to 92.7% of nonpoint source baseflow TDN loading comes from low and medium development intensity catchments, and sanitary infrastructure in wet areas of the landscape accounts for 39% of regional baseflow loading. Our research indicates that managing baseflow loading will require addressing lower development intensity catchments and sanitary infrastructure.

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Published In

Water Resources Research

DOI

EISSN

1944-7973

ISSN

0043-1397

Publication Date

July 1, 2022

Volume

58

Issue

7

Related Subject Headings

  • Environmental Engineering
  • 4011 Environmental engineering
  • 4005 Civil engineering
  • 3707 Hydrology
  • 0907 Environmental Engineering
  • 0905 Civil Engineering
  • 0406 Physical Geography and Environmental Geoscience
 

Citation

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Delesantro, J. M., Duncan, J. M., Riveros-Iregui, D., Blaszczak, J. R., Bernhardt, E. S., Urban, D. L., & Band, L. E. (2022). The Nonpoint Sources and Transport of Baseflow Nitrogen Loading Across a Developed Rural-Urban Gradient. Water Resources Research, 58(7). https://doi.org/10.1029/2021WR031533
Delesantro, J. M., J. M. Duncan, D. Riveros-Iregui, J. R. Blaszczak, E. S. Bernhardt, D. L. Urban, and L. E. Band. “The Nonpoint Sources and Transport of Baseflow Nitrogen Loading Across a Developed Rural-Urban Gradient.” Water Resources Research 58, no. 7 (July 1, 2022). https://doi.org/10.1029/2021WR031533.
Delesantro JM, Duncan JM, Riveros-Iregui D, Blaszczak JR, Bernhardt ES, Urban DL, et al. The Nonpoint Sources and Transport of Baseflow Nitrogen Loading Across a Developed Rural-Urban Gradient. Water Resources Research. 2022 Jul 1;58(7).
Delesantro, J. M., et al. “The Nonpoint Sources and Transport of Baseflow Nitrogen Loading Across a Developed Rural-Urban Gradient.” Water Resources Research, vol. 58, no. 7, July 2022. Scopus, doi:10.1029/2021WR031533.
Delesantro JM, Duncan JM, Riveros-Iregui D, Blaszczak JR, Bernhardt ES, Urban DL, Band LE. The Nonpoint Sources and Transport of Baseflow Nitrogen Loading Across a Developed Rural-Urban Gradient. Water Resources Research. 2022 Jul 1;58(7).
Journal cover image

Published In

Water Resources Research

DOI

EISSN

1944-7973

ISSN

0043-1397

Publication Date

July 1, 2022

Volume

58

Issue

7

Related Subject Headings

  • Environmental Engineering
  • 4011 Environmental engineering
  • 4005 Civil engineering
  • 3707 Hydrology
  • 0907 Environmental Engineering
  • 0905 Civil Engineering
  • 0406 Physical Geography and Environmental Geoscience